Low-redshift measurement of the sound horizon through gravitational time-delays

The matter sound horizon can be inferred from the cosmic microwave background within the Standard Model. Independent direct measurements of the sound horizon are then a probe of possible deviations from the Standard Model. We aim at measuring the sound horizon $r_s$ from low-redshift indicators, which are completely independent of CMB inference. We used the measured product $H(z)r_s$ from baryon acoustic oscillations (BAO) together with supernovae~\textsc{I}a to constrain $H(z)/H_{0}$ and time-delay lenses analysed by the H0LiCOW collaboration to anchor cosmological distances ($\propto H_{0}^{-1}$). {Additionally, we investigated the influence of adding a sample of quasars with higher redshift with standardisable UV-Xray luminosity distances. We adopted polynomial expansions in $H(z)$ or in comoving distances} so that our inference was completely independent of any cosmological model on which the expansion history might be based. Our measurements are independent of Cepheids and systematics from peculiar motions {to within percent-level accuracy.} The inferred sound horizon $r_s$ varies between $(133 \pm 8)$~Mpc and $(138 \pm 5)$~Mpc across different models. The discrepancy with CMB measurements is robust against model choice. Statistical uncertainties are comparable to systematics. The combination of time-delay lenses, supernovae, and BAO yields a distance ladder that is independent of cosmology (and of Cepheid calibration) and a measurement of $r_s$ that is independent of the CMB. These cosmographic measurements are then a competitive test of the Standard Model, regardless of the hypotheses on which the cosmology is based.Comment: 2019A&A...632A..91A (subm. 28/05/2019), 6 pages, 3 figure

The South African Constitution’s empty promise of “radical transformation”: unequal access to quality education for black and/or poor learners in the public basic education system

The South African Constitution mandates the radical transformation of the public basic education system. To that end, the Constitution, read with the South African Schools Act, entrenches a right of equal access to quality basic education for all. The substantive approach to equality, rooted in the transformative ideology of the Constitution, necessitates an acknowledgment and overcoming of the past patterns of disadvantage, based primarily on the grounds of race and socio-economic class. Locating my analysis in “quality education” in the United Nations Report, “Normative action for quality education”, I find that the definition of “quality education” involves a holistic approach which encompasses learners’ level of academic achievement, the provision of an adequate school infrastructure, a well-qualified teaching profession, and schools that embrace a substantive form of democracy. In examining each of these indicators, I find the emergence of a clear pattern: for black and/or poor South African learners in the public school domain, disadvantage manifests in an unequal access to quality education

Pointless or Profitable? Perceptions of Proactive Circles in a Second-Grade Classroom

Teachers are plagued with the unfortunate concept of “never enough time” in the classroom, trying to balance meeting the needs of the whole child and meeting the requirements of higher authority. The purpose of this study was to identify student and teacher perceptions of proactive circle and its impact on relationships, as well as its impact on students’ ability to appropriately express their feelings and emotions. The study took place in a second-grade classroom with seventeen students and one classroom teacher. Data was collected through surveys, sociograms, interviews, and field notes. Qualitative data was coded using the constant comparative method, and quantitative data was analyzed using frequency counts. Four major themes emerged including environment, circle, relationships, and introspection. The researcher identified a heightened awareness and voluntary vulnerability among students over the course of implementation, as well as the classroom teacher’s new found awareness for her students and their needs

Variation in breeding systems and consequences for reproductive traits in Erica

Includes bibliographical referencesErica makes up 7% of all species in the Cape flora. It is the most species-rich genus in the Cape Floristic Region (CFR), which has an area 0f 90 000km². Erica species have great inter- and intra-specific variation in floral form as well as in post-fire regeneration strategies. Previous studies of other plant groups (Barrett et al. 1996; Button et al. 2012) have illustrated changes in floral traits with a shift from outcrossing to selfing. The aim of this thesis was to determine whether similar changes occur in Erica. I thus analysed breeding systems in Erica in relation to floral traits, pollinators, and fire survivals strategies. Seed and fruit set data obtained from hand-pollination treatments suggested that self- fertilization occurs rarely. Autonomous selfing did not generally yield significant seed set. When comparing changes in floral traits with increased selfing ability and pollination syndromes weak relationships were observed. Average plant height showed a positive relationship with selfing ability but this correlation was not significant. Comparing traits within small and large flowered species separately yielded significant relationships between corolla size and selfing ability of small-flowered species.. Furthermore, general trends indicate that small-flowered species have increased ability to self-fertilise when corolla sizes are larger, corolla apertures larger and herkogamy reduced. Large-flowered species employ the same strategy but average corolla aperture is reduced. A trade-off between the size and the number of flowers was seen within the Erica genus. Small-flowered species had significantly more flowers compared to larger- flowered species that had markedly fewer flowers per unit height. This finding has implications for the selfing potential of small-flowered species as increased self- incompatibility may have evolved in order to reduce the effects of increased geitonogamy due to increased floral number. The prediction that self-fertilisation would be increased in seeders compared to resprouters, on the basis that seeders are more reliant on seeds for persistence than resprouters, was not realised when comparing the selfing ability of different fire- survival strategies. Erica mammosa, a species with morphs possessing both fire-survival strategies, shows no significant differences in selfing ability, this includes differences in pollen-ovule (P/O) ratios. However, indices suggest the resprouting form of E. mammosa to have an increased ability to self-fertilize while the seeder form has an increased ability for autonomous selfing. The 29 species analysed were divided into outcrossers and facultative outcrossers based on selfing indices but these did not fit neatly within Cruden’s proposed P/O ranges (facultative autogamy: P/Os= 32-397; facultative outcrossers: P/Os= 160.7 - 2258.6; outcrossers: P/Os= 1062 - 19525). This may be due to his classification of species into breeding systems being based on relatively few distantly related species per category with extremely variable P/O ratios per category. For example, outcrossers ranged an order of magnitude (from 1000+ to 20 000). It is also true that this ratio can be influenced by a variety of different factors, these include: habitat, evolutionary history and pollination syndrome. Consequently, P/O ratios in Erica do not seem to reflect pollination syndromes very well. Presumably, sex allocation theory may explain the relationship of breeding system with P/O ratios better. Histological studies of pollen tube growth for self- and cross-pollinated flowers of eight species suggested that Erica has late acting self-incompatibility (LSI). LSI is a barrier to selfing that occurs in the ovary. However, I could not determine if the rejection process occurs pre- or post-fertilization. Although, a large amount of knowledge is still lacking, this preliminary study provided insight into the reproductive biology of Erica

The Obligation to Provide Free Basic Education in South Africa: An International Law Perspective

In South Africa many learners are denied the right to basic education because of the levying of school fees and other educational charges, in spite of the international obligation imposed on government to provide free primary education. This article examines the exact nature and extent of this obligation by exploring the concept of "free" basic education. The applicable international instruments and their interpretation as well as the significance of the right to education as a central, facilitative right are examined in order to establish the content of the right to basic education and the legal obligations that ensue. Against this background, the implications of the South African Constitutional Court's approach to the realisation of socio-economic rights and the possibility of the establishment of a core minimum obligation are analysed. It is argued that learners in South Africa may come from different socio-economic backgrounds but as learners in the same public school domain and as equal bearers of their constitutional right to basic education all of them are entitled to the same type and quality of free basic education

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August SAMJ Cove

The school funding system and its discriminatory impact on marginalised learners

South Africa in reality harbours two separate education systems in its public school domain: one consisting of the former white schools, which is adequately resourced, and the other constituting the township and rural schools entrenched in abject poverty. The current school funding system perpetuates this state of inequalit